The oviduct is the site where the final maturation of gametes, fertilization and preimplantation embryonic development occur. The oviduct is also the site where most embryo mortality occurs. The goal of this project is to determine if the oocyte or cumulus cells affect the morphology of the oviduct or change the pattern of protein synthesis and secretion. To achieve this goal, one oviduct in each mouse will be ligated to allow the collection of oviducts that either have or have not been exposed to oocytes. The morphology and pattern of protein synthesis and release will be compared to assess whether the presence of cumulus oocyte complexes had any affect on oviduct function. Comparisons will then be made to oviducts exposed only to oocytes or to cumulus cells to determine which cell type causes the observed changes. This research creates a foundation for further investigation into the importance of paracrine interactions in fertilization and early embryonic development and may yield information that could be used to reduce the preimplantation loss of embryos and increase the success rate of in vitro fertilization.